usb: dwc3: of-simple: add support for shared and pulsed reset lines

Some SoCs (such as Amlogic Meson GXL for example) share the reset line
with other components (in case of the Meson GXL example there's a shared
reset line between the USB2 PHYs, USB3 PHYs and the dwc3 controller).
Additionally SoC implementations may prefer a reset pulse over level
resets.

For now this falls back to the old defaults, which are:
- reset lines are exclusive
- level resets are being used
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Tested-by: Yixun Lan <yixun.lan@amlogic.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/dwc3-of-simple.c

@@ -27,6 +27,7 @@ struct dwc3_of_simple {
 	struct clk		**clks;
 	int			num_clocks;
 	struct reset_control	*resets;
+	bool			pulse_resets;
 };
 
 static int dwc3_of_simple_clk_init(struct dwc3_of_simple *simple, int count)
@@ -83,6 +84,7 @@ static int dwc3_of_simple_probe(struct platform_device *pdev)
 
 	int			ret;
 	int			i;
+	bool			shared_resets = false;
 
 	simple = devm_kzalloc(dev, sizeof(*simple), GFP_KERNEL);
 	if (!simple)
@@ -91,16 +93,22 @@ static int dwc3_of_simple_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, simple);
 	simple->dev = dev;
 
-	simple->resets = of_reset_control_array_get_optional_exclusive(np);
+	simple->resets = of_reset_control_array_get(np, shared_resets, true);
 	if (IS_ERR(simple->resets)) {
 		ret = PTR_ERR(simple->resets);
 		dev_err(dev, "failed to get device resets, err=%d\n", ret);
 		return ret;
 	}
 
+	if (simple->pulse_resets) {
+		ret = reset_control_reset(simple->resets);
+		if (ret)
+			goto err_resetc_put;
+	} else {
 		ret = reset_control_deassert(simple->resets);
 		if (ret)
 			goto err_resetc_put;
+	}
 
 	ret = dwc3_of_simple_clk_init(simple, of_count_phandle_with_args(np,
 						"clocks", "#clock-cells"));
@@ -124,6 +132,7 @@ static int dwc3_of_simple_probe(struct platform_device *pdev)
 	return 0;
 
 err_resetc_assert:
+	if (!simple->pulse_resets)
 		reset_control_assert(simple->resets);
 
 err_resetc_put:
@@ -145,7 +154,9 @@ static int dwc3_of_simple_remove(struct platform_device *pdev)
 	}
 	simple->num_clocks = 0;
 
+	if (!simple->pulse_resets)
 		reset_control_assert(simple->resets);
+
 	reset_control_put(simple->resets);
 
 	pm_runtime_put_sync(dev);